JPH0262668B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a seismic isolation device. Conventionally, various proposals have been made as seismic isolation devices for heavy structures such as nuclear power plant buildings and bridge legs, and some of them have been put into practical use. As this type of seismic isolation device, one using flat laminated rubber is well known, but it has the following drawbacks. In other words, when the input seismic acceleration becomes large, for example 0.2 g or more, the structure is more likely to skid, and since it is mainly composed of elastic bodies, the hysteresis curve showing the absorption of seismic energy There was also a problem that the enclosed area was small. Therefore, in order to solve the above problem and obtain large energy absorption, we used the above laminated rubber and a soft metal that plastically deforms immediately when earthquake force is applied.
For example, a seismic isolation device combining lead with lead has been proposed. However, although such seismic isolation devices increase the ability to absorb seismic energy, when short-period vibrations such as strong winds act on a structure, contrary to an earthquake, the soft metal absorbs a relatively small external force. There is also the problem that the structure sways more than expected due to plastic deformation. This invention was made with the intention of solving the above-mentioned problems, and its purpose is to:
The object of the present invention is to provide a seismic isolation device that has a relatively large ability to absorb earthquake energy, has appropriate rigidity against external forces applied from the structure side, and is easy to install and replace. In order to achieve the above object, the present invention provides an upper structure in which an elastic body that supports a vertical load and deforms elastically in response to a horizontal load, and a rod-shaped body that deforms plastically through a predetermined elastic deformation in response to a horizontal load. A seismic isolation device installed between the base structure and the foundation structure, the elastic body comprising:
It has a flat elastic material and a metal plate that are alternately laminated, and the rod-shaped body is characterized by being made of a steel rod whose axis is positioned in the vertical direction. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 to 4 show an embodiment of a seismic isolation device according to the present invention. The seismic isolation device includes a superstructure 10 such as a building structure,
It is interposed between the foundation structure 12 and is composed of an elastic body 14 that supports a vertical load and deforms elastically in response to a horizontal load, and a rod-shaped body 16 that deforms plastically through a predetermined elastic deformation in response to a horizontal load. ing. The elastic body 14 is made by alternately laminating elastic sheets 14a made of neoprene rubber or the like in the shape of a flat plate and metal sheets 14b made of metal in the same shape with an adhesive interposed therebetween. It is constructed by attaching flat plate-like end plates 14c, 14c, and each end plate 14c, 14c is fixed to the above-mentioned upper structure 10 and foundation structure 12, respectively. This elastic body 14 exhibits a deformation σ property as roughly shown in FIG. 2 in response to a horizontal load Q. The rod-shaped body 16 is specifically a steel rod with a circular cross section, and has recesses 18, 18 formed opposite to the upper structure 10 and the foundation structure 12, and the recesses 18,
The upper and lower ends of the rod-shaped body 16 are loosely fitted into the rod-shaped body 18. Although such a loose fit structure is not necessarily required, if a loose fit structure is adopted, the rod-shaped body 16 can be attached or replaced even more easily. In response to a horizontal load Q, this rod-shaped body 16 exhibits a deformation σ property in which it reaches a yield point Pi through a predetermined elastic deformation region A, and then becomes a plastic deformation region B, as schematically shown in FIG. Here, the yield point Pi is given by the maximum horizontal load Q.
It is preferable to set it so that it is about 1/4 of that.More specifically, since the largest earthquake currently expected has a horizontal displacement of about 30 cm, the yield point Pi is about Set it to about 7.5cm. The deformation behavior of the seismic isolation device having the above-mentioned configuration in response to a horizontal load becomes a substantially parallelogram-shaped history curve as shown by the solid line in FIG. In other words, the seismic isolation device has properties that are a combination of the property curve of the elastic body 14 shown by the dashed line in the figure and the property curve of the rod-shaped body 16 shown by the dotted line. The present inventors set a specific reduced model of the above-mentioned seismic isolation device as follows and attempted vibration analysis. The elastic body 14 is a disc-shaped rubber sheet with a diameter of 150 mm and a steel plate, which are laminated to a thickness of approximately 250 mm, and the elastic modulus is set to 50 kg/cm.The rod-shaped body 16 is 13 mm in diameter and has a length of about 250 mm. We set a steel bar called a so-called PC steel bar C class No. 1 with a length of about 50 cm,
The spacing between 10 and 12 of the upper and substructure is 300mm.
It was set to The elastic modulus of the above steel bar is 112 kg/cm, and the yield point is the point at which it deforms by 1.8 cm under a horizontal load of 200 kg. In addition, the vertical load is 5 tons, and each of these values corresponds to about 1/40 of a 4- to 5-story concrete structure. The analysis results shown in Table 1 below were obtained by setting the above conditions.

[Table] From the above results, the seismic isolation device of the present invention has the following effects. That is, the currently assumed huge earthquake has a horizontal displacement of approximately 30 cm and a maximum period of 0.1 to 1.0 seconds, and σ = 8 cm in Table 1 above approximately corresponds to this value. Even for such a huge earthquake, the natural period of the entire system is long, 1.6 seconds, which is considerably larger than the earthquake period. Therefore, it is possible to prevent the amplitude from increasing due to resonance with the earthquake cycle. Additionally, the damping constant at each displacement is relatively large, effectively absorbing seismic energy. Furthermore, external forces such as strong winds applied to the building are received within the elastic region of the rod-shaped body 16, so the structure shakes less than a seismic isolation device using soft metals such as lead. Exhibits great rigidity. FIG. 5 is a schematic diagram showing another embodiment of the present invention, and only its characteristic points will be explained. In this embodiment, the rod-shaped body 16 is bent into a substantially S-shape and is installed together with the elastic body 14 between the upper structure 10 and the foundation structure 12. The end portions are fixed to the side surfaces of the base structure 12 and the base structure 12, respectively. Even in a device configured in this way, the seismic isolation device is
The characteristics shown in the figure are obtained. Vibration analysis was also performed on the seismic isolation device of this structure under the model conditions shown below. That is, the elastic body 14 and the upper part, the basic structure 1
The spacing between 0 and 12 and the vertical load are set to the same values as in the above example, and the S-shaped rod body 16 is made by folding a steel rod with a diameter of 22 mm at the same curvature so that its length becomes 300 mm. I set it to play. Table 2 below shows the results of analysis under the above conditions.

[Table] The elastic modulus of the S-shaped rod 16 is 87.2.
kg/cm, and the yield point was at σ = 2.3 cm under a horizontal load of 200 kg. Although the results in Table 2 above are slightly different from those in Table 1 above, T (period of the entire system) and heq (damping constant) have similar trends, and the same effect as in the above example can be obtained. It will be done. In each of the above embodiments, a single rod-shaped body 16 is used, but a plurality of rod-shaped bodies 16 may be loosely bundled with a string or the like and used. Furthermore, the bent shape of the rod-shaped body 16 in the second embodiment is S.
It may be not only a letter shape but also a U shape. As explained in detail in the embodiments above, in the seismic isolation device according to the present invention, a deformation property that combines an elastic body and a rod-like body is obtained, so that The area can be made relatively large, the period of the system can be separated from the earthquake period, problems caused by resonance can be avoided, and since the axis of the rod-shaped body is located in the vertical direction, the vertical It can be easily installed between the upper structure and the foundation structure located in the same direction, and it can also be replaced easily, which provides various excellent effects.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the installed state of the seismic isolation device according to the present invention, Fig. 2 is a characteristic diagram of the elastic body, Fig. 3 is a characteristic diagram of the rod-shaped body, and Fig. 4 is a characteristic diagram of the seismic isolation device. FIG. 5 is a schematic diagram of another embodiment. 10...Superstructure, 12...Foundation structure, 14...
...Elastic body, 16... Rod-shaped body, 18... Recess.

Claims (1)

[Claims] 1. An elastic body that supports a vertical load and deforms elastically in response to a horizontal load, and a rod-shaped body that undergoes a predetermined elastic deformation and plastically deforms in response to a horizontal load are combined into a superstructure and a foundation structure. A seismic isolation device installed between A seismic isolation device characterized by comprising: 2. The seismic isolation device according to claim 1, wherein the steel rod is bent into a substantially S-shape or U-shape.